Power bank



FIG. 1 is a perspective view of the power bank;

FIG. 2 is a front view of the power bank;

FIG. 3 is a back view of the power bank;

FIG. 4 is a left side view of the power bank;

FIG. 5 is a right side view of the power bank; and

FIG. 6 is a top view of the power bank; and,

FIG. 7 is a bottom view of the power bank. 

CLAIM The ornamental design for a power bank, as shown and described. 